CDKN1A and neoplasm: Albeit it has been established that BRAFV600E promotes senescence or apoptosis without yielding any previous proliferative stimulation in vitro [51, 56], BRAFV600E expression in vivo results in an initial hyperplasic wave lastly culminating in the onset of tumor senescence, characterized by DNA damage [17], and p21CIP1 [17], p19ARF [9], p16INK4a [21] and p53 [57] expression.